Human Papillomaviruses (HPVs) cause benign and malignant tumors of the genital tract and airway. Recurrent Respiratory Papillomatosis (RRP), caused by HPVs type 6 and 11, is a disease with a high degree of morbidity and significant mortality. It is characterized by the growth of benign tumors in the airway. The current treatment for this disease is surgical removal of the papillomas. Recurrence frequently necessitates that patients undergo surgery four times a year, even more frequently in the most severe cases. Recurrence is mediated by activation of the latent HPV infection, however, little is known about the mechanism of HPV activation, characterized by increased viral expression. The long term goal of our studies is to enable the development of targeted treatments for HPV-induced disease. In particular, the goal of this proposal is to investigate the role of altered cellular signal transduction on HPV expression in the development of papillomas. The Rac1 small GTPase is known primarily for its regulation of the actin cytoskeleton, but it also regulates cell proliferation, resistance to apoptosis and many other cell functions. Rac1 is overexpressed in papillomas. Interestingly, preliminary data indicate that Rac1 is overexpressed in clinically normal airway tissue in RRP patients. Rac1 overexpression is thought to stimulate tumor progression and is associated with many carcinomas. This proposal will investigate the role of Rac1 overexpression and downstream signal transduction pathways on HPV expression. This project will test the hypothesis that constitutive Rac1 overexpression in RRP patients enhances expression of HPV through activation of one or more signal transduction pathways that act on the viral upstream regulatory region. The specific aims are to test the hypothesis that high levels of Rac1 enhance HPV expression and to determine the signal transduction pathway(s) that enhance HPV expression and identify the responsible viral sequence. HPV DNA will be transduced into normal laryngeal keratinocytes from a non-RRP patient and normal laryngeal keratinocytes isolated from RRP patients, which have high levels of Rac1, and viral copy number and gene expression will be compared. Furthermore siRNA and specific signal transduction inhibitors will be used to identify which pathway(s) downstream of Rac1 contribute to enhanced HPV expression in immortalized papilloma cells. The viral sequences that are targeted by these pathways will be identified using sequential 5' truncation mutants and select point mutants of the HPV 11 upstream regulatory region (URR) expressed in RRP-N cells. In addition to the research proposed, the research training program will include training in the responsible conduct of research; courses in translational research; formal and informal training in grantsmanship; participation in scientific meetings; and mentored guidance in public speaking, manuscript review and mentorship of students and fellows. PUBLIC HEALTH RELEVANCE: Human Papillomaviruses (HPVs), which cause benign and malignant tumors of the genital tract and airway, infect over 80% of sexually active women. Preliminary results from studies of the HPV-induced disease Recurrent Respiratory Papillomatosis suggest that the signaling molecule Rac1 promotes HPV expression. This research project will elucidate the effects of Rac1 on HPV expression, thereby providing novel drug targets to help control HPV infections.